MRU 3

Motion Reference Unit

MRU 3 is the fifth generation roll, pitch and heave motion sensor designed especially for heave compensation applications, such as for use with echosounders, fishing sonars and offshore cranes. This product stands out by delivering precise heave measurements that adhere to IHO standards, providing functionality critical for maritime operations.

Advanced Sensor Technology for Precision

This cost-effective MRU 3 model is built on 3-axis Micro-Electro-Mechanical-Structures (MEMS) sensors, providing accurate and reliable measurements for both linear acceleration and angular rate, thanks to solid state sensors with no rotational or mechanical wear-out parts. The MRU 3 also comes with a Windows-based configuration and data presentation software, which allows for defining vector arms from the MRU's mounted location to the centre of gravity (CG) and two configurable monitoring points. These precise outputs and configuration options make the MRU an invaluable tool for maritime operations.

Superior Data Integration and Output

MRU 3 stands out with its ability to deliver real-time roll, pitch, and heave measurements along with linear acceleration across three axes. The unit outputs heave position and velocity and the angular rate vectors for roll and pitch. With the latest PFreeHeave algorithm, MRU 3 can output correct and phase-free heave data, an advantage for applications such as seabed mapping. Utilizing external speed and heading input together with time synchronization features, the MRU 3 ensures improved accuracy even during vessel turns and accelerations.

Optimized Connectivity for Various Applications

Ensuring versatility for users, the fifth generation MRU is equipped with Ethernet interface and serial lines that allow for easy data distribution to multiple users on board the vessel. The unit boasts a high data output rate and compatibility with various digital I/O protocols, ensuring seamless operation with commonly used survey equipment. In addition, the MRU 3 features selectable communication protocols in its configuration software, underscoring the sensor's adaptability to specific maritime data systems and requirements.

Key features

  • 0.08° roll and pitch accuracy
  • Outputs real-time roll, pitch, and heave measurements
  • Outputs on RS-232, RS-422, and Ethernet
  • High output data rate (200 Hz)
  • Precise heave at long wave periods by use of PFreeHeave algorithms
  • Lever arm compensation to two individually configurable monitoring points
  • Small size, light weight, and low power consumption
  • Each MRU delivered with Calibration Certificate
  • Selectable communication protocols in the Windows based MRU configuration software
  • Export license not required
  • 2-year warranty

Technical specifications

Output

Roll/pitch Static RMS:
0.08°
Roll/pitch Dynamic 1-sigma:
0.010°
Heave Real-time RMS:
5 cm/5 %
Heave Period Real-time:
18 s
Heave Delayed RMS:
2 cm/2 %
Heave Period Delayed:
50s

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